I'm drawing a line using OpenGL on the iPhone. I used GLView and GLKView delegates to draw the line. But now I want to set a background image to GLKViewController, and on the background image, I want to draw the line. I have tried to set a background image using UIImageView, but the image is appearing above on the (GLKView) drawn line.
How can I set a background image to the GLKViewController?
The easiest way should be to add additional view with background image (such as you proposed - but you need to set it behind OpenGL view). Try this:
[RootViewController.view addSubview: BackgroundView belowSubview: OpenGLView];
OpenGLView.opaque = NO;
But this will bring some FPS penalty (Apple recommends to use opaque OpenGL view for performance reason). More correct approach is to draw background via OpenGL as fullscreen quad.
I just want to state that the accepted answer is a very bad one... You will lose an almost immediate 20fps even on the newer devices (iPhone 5, iPad 2 & newer) by turning off opaque. The performance penalty is horrible and should not be taken lightly.
You can set a background in OpenGL and keep your opaque. Convert the UIImage to an OpenGL texture and render it. Depending on your OpenGL environment, this can be done a number of ways easily.
